mt90503 Zarlink Semiconductor, mt90503 Datasheet - Page 67

• Manufacturer Part Number: mt90503
• Description: 2048vc Aal1 Sar
• Manufacturer: Zarlink Semiconductor

CE
BS
Last Entry
TXD
Field
Table 22 - Description of the Fields for the TX_SAR Control Structure (continued)
Circuit
Emulation
TX/RX
Circular
Buffer Size
Last Entry
TX_SAR
Destination
Field
Name of
Field
+0/b4:b2
+0/b1:b0
+2/b15:b4
+2/b3:b0
Offset /Bits
Address
Used
Byte
Zarlink Semiconductor Inc.
The CE field bits indicate the presence of a multiframing
standard used within the VC.
The multiframing standard changes the way the information is
read from the TDM circular buffers, as well as the standard
that is used to generate the p-byte. In addition, setting the CE
bits to a CAS setting will indicate to the TX_SAR that CAS
signaling bits must be inserted at the end of the AAL1 control
structure.
The field bits are decoded as follows:
000 = No CAS, no multiframe
001 = Reserved
01x = Reserved
100 = T1 without CAS (T1 type circular buffer, but no CAS will
be sent in the ATM cells)
101 = T1 with CAS (T1 type circular buffer, with CAS sent in
the ATM cells
110 = E1 without CAS (E1 type circular buffer, but no CAS will
be sent in ATM cells)
111 = E1 with CAS (E1 type circular buffer, with CAS sent in
the ATM cells
These bits encode the size of the TDM circular buffer that is to
be read from. In T1 and E1 modes, a portion of space in the
circular buffer is required to store the CAS values; in the T1
mode 25% is required, and in the E1 mode 50% is required.
Half of the TDM circular buffer is used for TX data and half for
RX data.
The field bits are decoded as follows:
00 = 128 words
01 = 256 words
10 = 512 words
11 = 1024 words
Last Entry is the word offset from the 8 kB boundary containing
the structure to the last circular buffer pointer in the structure.
The TXD field is used to tell the UTOPIA Module the
destination of the assembled ATM cell.
The TX_SAR Destination field is decoded as follows:
0000 = Discard ATM cell
0XX1 = Send to TXA port
0X1X = Send to TXB port
01XX = Send to TXC port
Others = Reserved
Broadcasting to multiple ports is allowed.
MT90503
67
Description of Field
Data Sheet